Where the contents are a burning substance, it is known to provide a flexible seal assembly which is held together by rivets or the like, passing through metallic strips trapping an end of the assembly. Such an example is described and illustrated in published GB patent specification 1,279,468.
A disadvantage of the published disclosure is that the assembly has to be held together by means other than the rivets, until the rivet holes are drilled and while fixing of the rivets is effected. Alternatively, the rivet holes may be drilled in each individual part prior to assembly, and then aligned during the holding of the parts together by some means, so as to enable fixing of the rivets. Both methods are time consuming operations.